An optical device for use at a computer work station enables a worker to magnify visual displays on a computer screen. The optical device helps workers to view a screen more easily, in greater detail, or from a more distant location, thereby preventing or reducing eyestrain, back pain, and other problems caused by extensive use of computer screens. The optical device is especially useful for helping workers with presbyopic eyesight to see computer screens.
It is well known that the operation of computer monitors, video terminals, and the like in which the operator is required to view a screen for extended periods of time may cause operator eyestrain. The operation of computers has often been the source of back problems, headaches, and other ailments. This is especially true for computer operators, including word processors, secretaries, data processors, designers, financial professionals, or others who spend a considerable amount of time working at computer screens.
Maintaining an ergonomically correct posture may help avoid physical ailments associated with the use of computer screens. An ergonomically correct position, however, may be difficult to maintain under typical circumstances. For example, computer operators must simultaneously view a monitor screen, operate a computer key board and periodically view or write on various documents or files. Computer operators may need to move about and chance work positions or engage in diverse tasks, such as working at an adjacent desk or answering a phone. Such movement may require increased separation from the computer screen and/or a change in the viewing angle. These circumstances can be challenging in terms of maintaining an ergonomically correct position.
Even when maintaining an ergonomically correct position, any difficulty or deficiency in seeing the screen can lead to ailments such as eyestrain or headaches. Yet any visual problems in seeing the screen is likely to make it more difficulty to maintain an ergonomically correct position which will worsen such ailments or potentially lead to additional ailments such as backache or other musculoskeletal disorders or conditions. Moreover, it is not uncommon for such a disorder to insidiously develop over time, even over a period of years, becoming apparent only after the disorder has progressed to a point where it has become serious in nature and/or is difficult to reverse.
Persons who are presbyopic (xe2x80x9cpresbyopesxe2x80x9d) have special problems in seeing computer screens. Everyone becomes presbyopic with after, usually beginning after a person reaches the mid forties. Presbyopia is when a person""s eyes lose their natural flexibility for focusing on near objects, also referred to as a decline in accommodative ability. The range of accommodation is the distance (measured from the eye) to which an object can be carried toward the eye and kept in focus, and the power of accommodation is the dioptric equivalent of this distance, a standard unit of measurement in the ophthalmic field.
This loss of accommodation is believed due, at least partly, to a hardening of the lens of the eye with age. Normal eyesight can deteriorate to the point where at age 55, sharply focusing on anything within three feet is not possible without aid. As a consequence, most older people eventually require spectacles to assist them in short-distance vision, in order to see clearly when reading or doing close work. Several products are available for this purpose, including reading spectacles, bi-focals, and multi-focal or progressively graded spectacles. Each of these approaches has its own drawbacks or limitations while working with computers.
The nature of a computer work station is such that the computer monitor screen is usually located within the area a person with presbyopia would need bifocals, but is higher in the viewing plane than is corrected by such lenses. This leads to repeated head bobbing, as well as leaning forwards or backwards, in order to focus on the monitor, the key board, and possibly even a copy stand or document holder. Moreover, reading spectacles or bi-focals are limited to a single diopter power optimally designed for reading at a single predetermined distance. Computer screens may be positioned at a different distance (often a greater distance) from the eye than the distance a book is typically placed, particularly at certain moments when the computer operator increases his or her distance from the computer in order to view another object, such as a document or file on an adjacent desk. Moreover, the stronger the lens in bifocals or reading spectacles, the shorter will be the patient""s range of focus. The loss of range can present difficulties to the computer operator who must see the computer screen, the keyboard and a documents at various distances.
Progressively graded spectacles allow correction for a continuum of distances, and have the advantage of permitting the user to instantaneously change focus in accordance with a change in viewing angle. With progressively graded lenses, however, focal distance strictly depends on the direction of viewing which is not necessarily commensurate with environmental requirements. The largest power grading typically starts at low angles for reading, and becomes gradually lower for higher angles and thus longer distances. In general, the extent of such a power variation is about 2.5-3 diopters from the lowest to the highest viewing angle. This variation of power as a function of viewing angle, as dictated by any progressive grading technique, is restrictive because the objects in an environment viewed by an observer rarely exhibit a spatial positioning that is exactly complementary to the grading. In most scenarios, the line of sight of a near object is lower than that of more distant objects, but this is not always the case. Consequently, viewing a computer screen at the same time as a document at a lower position may not be possible without an unnatural or inconvenient tilting of the head of the wearer, and this may increase the chances of an ergonomically poor posture or movement.
Various types of optical apparatus have been proposed to alleviate or reduce the eyesight difficulties of presbyopic and non-presbyopic individuals involved in working with computer screens. Such optical apparatus are commonly placed between the operator and the computer screen in order to magnify the screen. For example, U.S. Pat. No. 4,712,870 to Robinson and U.S. Pat. No. 4,577,928 to Brown disclose the use of Fresnel lenses that are interposed between the monitor and the operator to magnify the monitor screen image. An adjustable lens holder for a magnifying lens in the context of a computer screen is also disclosed in U.S. Pat. No. 4,529,268 to Brown, and U.S. Pat. No. 4,958,907 to Davis.
Although such prior-art image magnification devices may provide certain benefits, they suffer from serious deficiencies and limitations which have certainly limited their popularity. One problem with such prior-art magnifiers is that they employ Fresnel lenses. While having the advantage of being lightweight and inexpensive, Fresnel lenses have the disadvantage of exhibiting a pattern of fine concentric circles or the like that is cut into the surface of the lens in order to flatten the lens shape, which pattern is unattractive and detracts from the clarity of detail seen through the lens. Furthermore, a Fresnel lens placed relatively close to a computer screen does not adequately help presbyopes, because although the lens enlarges the lettering, the lettering remains fuzzy and cannot be brought into sharp focus. While a Fresnel lens with a larger focal distance may be placed a greater distance from the computer screen, the clarity of a Fresnel lens tends to decrease with increasing distance from the screen or object being magnified.
Another problem with prior-art computer magnifiers has been that they do not adjust very well to the changing positions of a computer operator and/or to the changing visual needs of the operator. For example, different persons in the same family may use the same computer monitor at home, or different persons in the same work group, or a temporary substitute, may use the same computer monitor at the office. Or the same person may have different visual needs when performing different computer tasks or viewing different images. Prior-art magnification devices may provide for adjusting the lens location to some extent, but the adjustment may be discontinuous or lacking in certain directions, and the range of lens movement may be relatively limited.
Another problem that persons encounter when using computer screens is that it may not be possible for an entire page of a document or drawing to be contained within a single visual display on the computer screen without the visual display or its details becoming too small to see without difficulty. For example, an entire spreadsheet or engineering drawing may be too small to xe2x80x9creadxe2x80x9d when viewed in its entirety on a computer screen. Thus, instead of viewing the page of a drawing or spreadsheet at one time (as an integral whole), it may be necessary to view the page in parts, for example, by tabbing back and forth, or up and down, along the page in order to sequentially change the part of the page being viewed at any given point in time.
It would be highly desirable to provide an optical device for use at a computer work station to magnify the image on a monitor screen while providing adequate flexibility for readily adjusting to the ergonomic and visual needs of the operator.
It would be highly desirable to provide an optical device for use at a computer monitor that would, in effect, increase the effective size of a screen, for example, that would increase the size of print on a smaller 13-inch monitor to the size of print on a larger 17-inch monitor, so that a smaller monitor can be viewed with the same ease as a larger monitor.
It would be highly desirable to provide an optical device that would allow computer operators to see more information on a computer screen than would otherwise be possible (in spreadsheets, drawings, schedules, and financial information.) It would be highly desirable to provide an optical device that would allow computer operators to more easily view, at one time in a single image, an entire page that otherwise could only be viewed in parts.
It would be highly desirable to provide an optical device for use with a computer monitor that would enable operators having presbyopia to more easily and more clearly see screen images.
It would be highly desirable to provide an optical device for use with a computer monitor that would provide for adjusting the position of a magnification lens in a manner that quickly and filly responds to the changing needs of the same or different computer operators.
It would also be advantageous to provide such an optical device that could be readily and conveniently retrofitted to existing computer work stations.
The present invention is directed to apparatus and methods for magnifying the screen of a computer monitor, video display terminal, or the like. The invention is especially useful for a computer work station to enable a worker to magnify the visual display on a screen of a computer monitor. The apparatus comprises an adjustable arm for supporting a magnifying lens between the worker and the screen of the computer monitor viewed by the worker.
The adjustable arm comprises (1) a vertical structural unit that is attached to a base support, preferably in back of the computer monitor with respect to the operator, which vertical structural unit extends in a generally vertical direction from said base support, preferably to a vertical position higher than the back of the computer monitor, (2) a horizontal structural unit that is attached to the upper end of the vertical structural unit in an elbow and which horizontal structural unit extends past the computer monitor to a position in front of the computer with respect to the worker. The far end of the horizontal structural unit is attached to the magnifying lens in front of the screen. The adjustable arm is supported independently of the operator""s body by a weight that is equal to or greater than the total weight of the computer monitor. In other words, the adjustable arm is attached to a base support, the horizontal planar surface of which is below the computer monitor such that the full weight of the computer monitor can be used to counterbalance the force exerted by the arm at its attachment to the base support. This arrangement supports a non-Fresnel lens at a variable distance from the monitor screen.
Preferably, the magnifying lens is continuously movable in a vertical, horizontal and axial direction. The lens has a combination of properties that, in the context of a computer screen and adjustable positioning, allows presbyopic operators to more clearly and more easily see the images on a computer screen.
The optical device of the present invention can prevent or reduce eyestrain, back pain, and other such problems caused by extensive use of a video or computer screen. It provides greater flexibility for meeting the visual or ergonomic needs of the individual worker. For example, the invention allows a computer operator a greater range of options and positions for viewing the screen through the magnifying lens by providing a greater range and ease of movement of the lens vis-à-vis the screen. The optical device also enables an operator to obtain an enlarged view of a visual display, which is particularly advantageous for viewing pages of spreadsheets, figures, or the like that are otherwise too small to be viewed as a single image on a screen.
The invention is especially beneficial for presbyopic operators. When viewing screen images through the magnifying lens of the present invention, the amount of eye accommodation necessary to view screen images can be reduced or eliminated, thereby allowing presbyopic operators to see screen images more clearly.